Fuel injector devices

ABSTRACT

A fuel injector device in which the fuel flow path through the device includes a variable area metering orifice, the area of the orifice being adjusted in response to changes in fuel pressure at the injector device inlet. The orifice is formed by cooperation between one valve member and a fuel port in another valve member. The valve members are movable relative to each other and the fuel port extends in the direction of the relative movement and has a cross-sectional area which varies in that direction. A pressureresponsive member, for example a resilient diaphragm, senses the fuel pressure at the injector device inlet and causes relative movement between the valve members in response to changes in that pressure, to vary the area of the metering orifice. The fuel port may have a triangular cross-section, with both the base and height of the triangle increasing together along the fuel port in the direction of relative movement, whereby changes in the area of the metering orifice bear a &#39;&#39;&#39;&#39;square law&#39;&#39;&#39;&#39; relationship to changes in the inlet fuel pressure of the injector device.

United States Patent Jackson [54] FUEL INJECTOR DEVICES [72] Inventor: Harold Ernest Jackson, Plympton St. Mary, England [73] Assignee: Petrol Injection Limited, Plymouth,

Devon, England 221 Filed: Nov. 27, 1970 [211 Appl.No.: 92,987

Primary Examiner-M. Henson Wood, Jr. Assistant ExaminerEdwin D. Grant Attorney-Holcombe, Wetherill & Brisebois [451 Oct. 3, 1972 ABSTRACT A fuel injector device in which the fuel flow path through the device includes a variable area metering orifice, the area of the orifice being adjusted in response to changes in fuel pressure at the injector device inlet. The orifice is formed by cooperation between one valve member and a fuel port in another valve member. The valve members are movable relative to each other and the fuel port extends in the direction of the relative movement and has a crosssectional area which varies in that direction. A pressure-responsive member, for example a resilient diaphragm, senses the fuel pressure at the injector device inlet and causes relative movement between the valve members in response to changes in that pressure, to vary the area of the metering orifice. The fuel port may have a triangular cross-section, with both the base and height of the triangle increasing together along the fuel port in the direction of relative movement, whereby changes in the area of the metering orifice bear a square law" relationship to changes in the inlet fuel pressure of the injector device.

9 Claims, 5 Drawing Figures PATENTEBIJEI 3 m2 SHEET 3 BF 3 FUEL INJECTOR DEVICES This invention relates to fuel injector devices for fuel injection systems for internal combustion engines and, in particular, to injector devices which are suitable for use in systems in which fuel is pressurized in dependence on at least one engine operating parameter.

The present invention provides a fuel injector device for a fuel injection system of an internal combustion engine, including two valve members which are movable relative to each other and a first one of which includes a fuel port which cooperates with the second valve member to define a fuel metering orifice in the fuel flowpath between the inlet and the outlet of the injectordevice, the fuel port extending in the direction of the said relative movement and having a cross-sectional area which varies along the fuel port in that direction whereby the area of the metering orifice is adjustable by relative movement between the valve members, and a pressure-responsive member exposed to fuel pressure at the injector device inlet and coupled to at least one of the valve members to cause relative movement between the valve members and thereby adjust the area of the metering orifice in response to variations in that fuel pressure.

The fuel port may have any suitable cross-sectional shape. Preferably, however, the cross-sectional area of the fuel port varies through variations in two dimensions of the cross-sectional shape of the fuel port, since this enables changes in the area of the metering orifice to follow a square law relationship to changes in the inlet fuel pressure of the injector device. The fluid port may, for example, have a substantially triangular crosssection, the height and base of the triangle varying (and preferably increasing together) along the fuel portin the direction of the said relative movement.

One of the valve members may be a cylindrical element and the other valve member may then be a casing member within which the cylindrical element is located. The valve members may be movable relative to each other in the direction of the axis of the cylindrical'element. If the first valve member is a cylindrical element, then the fuel port may be defined in the outer curved surface of the valve member: in one embodiment of the invention, the first valve member is a tubular element and the fuel port, which is defined in the outer curved surface of the valve member, communicates with the bore of the tubular element.

The invention also provides a fuel injection system for an internal combustion engine, including .a plurality of injector devices each constructed in accordance with the invention, the inlets of the injector devices being connected to receive fuel from a pressurizing device operable to pressurize fuel in dependence on at least one engine operating parameter. The fuel pressurizing device may be operable to pressurize fuel in dependence on engine air intake. The pressurizing device may, for example be of the type disclosed in the Complete Specification of British Pat. applications Nos. 1261/69, 32530/69 and 58515/69, (Ser. No. 1254,181) having a mechanism operable to produce a control pressure differential over a portion of the air supply path to the engine and adjustable to maintain that pressure differential substantially constant, operation of the fuel pressurizing device being dependent on the said adjustment of the control mechanism.

By way of example, a fuel injector device constructed in accordance with the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a cross-section of the injector device;

FIG. 2 is a view on an enlarged scale of one of the components of the injector device taken on the line II-II in FIG. 1;

FIG. 3 is a scrap view in the direction of the arrow III in FIG. 2; and

FIG. 4 is a diagram of a fuel injection system including a plurality of injector devices of the type shown in FIGS. 1 to 3.

The fuel injector device shown in FIG. 1 has an outer casing defining a body portion 1 from which projects an elongated nozzle 2. The fuel inlet 3 of the injector device communicates witha chamber 4 formed within the body portion 1 and separated, by a pressureresponsive member in the form of a resilient diaphragm 5, from a further chamber 6 in the body portion.

The nozzle 2 contains a valve comprising first and second valve members formed by an elongated tubular element 8 and the outer casing of the nozzle respectively. The elongated tubular valve member 8 extends into the chamber 4 and terminates, within the chamber 4, in an enlarged head portion 10. The other end of the valve member 8 projects through an outlet 11 formed in the outer casing at the distal end of the nozzle 2, as shown in FIG. 1 outer casing. The valve member 8 is a-sliding fit within the outer casing at the outlet 11 and adjacent the body portion 1, so that it is axially movablewithin the outer casing in a direction into and out of the chamber 4.

A fuel port 12 (See FIGS. 2 and 3) is formed in the outer curved surface of the valve member 8 adjacent the heat portion 10 and communicates with an openended central passageway 13 formed within and extending to the distal end of the valve member. A stop 14 is located around the valve member 8 and a spring 15, located between this stop and! the distal end of the nozzle casing, urges the valve member into the chamber 4 and towards the diaphragm 5. The diaphragm 5 in turn, is urged. towards the valve member 8 by a spring 7 located in the chamber 6 in the body portion 1 and seated on a plate 16 secured to the diaphragm.

When the injector device is not being supplied with fuel, the valve member 8 takes up a position in which the head 10 of the valve member is engaged by the diaphragm 5 and the forces exerted on the valve member, by the springs 15 and 7 are balanced. In this position, the fuel port 12 lies completely within the nozzle portion 2 of the injector device and is closed by the nozzle casing as shown in FIG. 1. If fuel is now supplied under pressure to the injector device inlet 3, the fuel pressure acts on the diaphragm 5 from within the chamber 4 and, if sufficiently great, moves the diaphragm away from the head 10 of the valve member 8 against the bias of spring 7. This, in turn, allows the valve member 8 to move into the chamber 4 under the bias of spring 15 with the result that the fuel port 12 now lies partly within the chamber 4, and is uncovered, the extent to which the port is uncovered being determined by the fuel pressure at the inlet 3. Fuel can now flow from the chamber 4 through the metering orifice defined by the uncovered portion of the fuel port 12, and along the passage 13 within the valve member and is discharged at the distal end of the nozzle portion 2 through the outlet 11. If fuel pressure at the inlet 3 increases then the valve member 8 is allowed to move further into the chamber 4 and the fuel port 12 is uncovered to an even greater extent: this, as a result of the particular shaping of the fuel port to be described below, increases the area of the metering orifice and allows more fuel to be discharged by the injector device. If, on the other hand, fuel pressure at the inlet 3 decreases then the valve member 8 is moved, by the spring 7 acting on the diaphragm 5, back into the nozzle 2 to decrease the extent to which the fuel port 12 is uncovered. If the fuel supply to the inlet 3 ceases altogether, or the fuel pressure drops below a certain value, the spring 7, acting through the diaphragm 5, moves the valve member 8 back completely into the nozzle 2 and closes the fuel port 12.

A stop 17, the position of which is adjustable from the exterior of the injector device by a screw 18, is located in the chamber 6 and limits the travel of the diaphragm away from the valve member 8 and hence movement of the valve member into the chamber 4.

The fuel port 12 is substantially triangular in crosssection when viewed along the axis of the valve member 8, as shown in FIG. 2. The area of the triangle increases, in moving along the axis of the valve member, from zero to a maximum (at which point the fuel port is in communication with the fuel passageway 13) and then decreases again to zero. As a result, an increase up to a certain maximum value in fuel pressure acting on the diaphragm 5 in chamber 4 causes an increase in the area of the metering orifice defined by the uncovered portion of the fuel port 12, and hence an increase in fuel flow through the injector device. When the above-mentioned maximum fuel pressure is reached the metering orifice is completely open and a further increase in fuel pressure will not be accompanied by a corresponding increase in fuel flow.

It can be seen from FIGS. 1 and 3 that the base and height of the triangular cross section of the fuel port 12 increase together in moving along the axis of the valve member 8. This particular shaping is advantageous in that changes in the area of the metering orifice defined by the fuel port 12 then follow a square law relationship to axial movement of the valve member 8 and hence to changes in the fuel pressure at the inlet 3. In other words, axial movement of the valve member 8 is accompanied by a comparatively large change in the area of the metering orifice. In addition, the fuel port 12 shown in FIGS. 1 to 3 can be easily formed by a simple machining operation namely, running a triangularshaped cutting tool along a straight line intersecting the axis of the valve member 8. This particular shaping of the fuel port is, however, not essential and other forms could be employed. In some circumstances, for example, variation in one dimension only of the cross-sectional shape of the fuel port 12 may be sufficient. It will be appreciated that, in general, the shape of the fuel port will be chosen having regard to the desired fuel flow/fuel pressure characteristic of the injector device.

" FIG. 4 shows a plurality of injector devices 20 each of which is of the type shown in FIGS. 1 to 3, connected in the fuel injection system of an internal combustion engine. The system is similar to that described in British Pat. application No. 32530/69 (Ser. No. 1,254,181) and reference may be had to that Application for a more detailed description of the various components of the system. Briefly, the system includes a tank from which fuel is drawn by a pump 101 and supplied to the injector devices 20 via a supply conduit 102 and a pressure control valve mechanism 103. Excess fuel is returned from the valve mechanism 103 to the tank 100 via a relief valve 104.

The valve mechanism 103 controls the pressure at which fuel is supplied to the injector devices 20, in dependence on engine air in-take. The manner in which this control is effected is described in detail in British Pat. application No. 32530/69 (Ser. No. 1,254,181): briefly, however, the system includes an air valve 105 located, in addition to the customary throttle valve 106, in the conduit 107 which feeds air to the engine, and a manifold depression control device 108 which senses the depression between the valves 105, 106 and, through a linkage 109, adjusts the position of the air valve 105 to maintain the depression at a substantially constant value. The pressure control mechanism 103 senses the position of the air valve 105 through a conduit 110 and adjusts the pressure of fuel supplied to the injector devices 20 as the position of the air valve varies. The particular arrangement shown in FIG. 4 by which the conduit 110 communicates with the air intake conduit 107 is described in British Pat. application No. 58515/69 (Ser. No. 1,254,181). Variations in the pressure of the fuel supplied to the injector devices 20 result in movement of the valve members 8 (FIG. 1) of the injector devices to adjust the amount of fuel flowing through the device accordingly. The injector devices 20 are positioned to discharge fuel into the intake passages of the engine cylinders, or directly into the cylinders.

It will be appreciated that use of the injector devices shown in FIGS. 1 to 3 is not restricted to systems of the type shown in FIG. 4 and that the devices could be employed in any system in which fuel is pressurized in dependence on an engine operating parameter.

I claim:

1. A fuel injector device for a fuel injection system of an internal combustion engine, including a fuel inlet, a fuel outlet and a fuel flow path between the inlet and the outlet, first and second valve members which are movable relative to each other, the first valve member being a tubular element having, in the outer curved surface thereof, a fuel port which communicates with the bore of the tubular element and cooperates with the second valve member to define a fuel metering orifice in the said fuel flow path, the fuel port extending in the direction of the said relative movement and having a cross-sectional area which varies along the fuel port in that direction whereby the area of the metering orifice is adjustable by relative movement between the valve members, and a pressure-responsive member exposed to fuel pressure at the injector device inlet and coupled to at least one of the valve members to cause relative movement between the valve members and thereby adjust the area of the metering orifice in response to variations in that fuel pressure.

2. An injector device as claimed in claim 1 in which the cross-sectional area of the fuel port varies through variations in two dimensions of the cross-sectional shape of the fuel port.

3. An injector device as claimed in claim 2, in which the fuel port has a substantially triangular cross-section and the base and height of the triangle vary along the fuel port in the direction of the said relative movement.

4. An injector device as claimed in claim 3, in which the base and height of the triangle both increase together along the fuel port in the direction of the said relative movement.

5. An injector device as claimed in claim 1, in which the valve members are movable relative to each other in the direction of the longitudinal axis of the first valve member.

6. An injector device as claimed in claim 1, in which the second valve member is a casingmember within which the first valve member is located.

7. An injector device as claimed in claim 1, in which the pressure-responsive member is a resilient diaphragm.

8. An injector device as claimed in claim 7, in which one of the valve members is resiliently biased into engagement with the diaphragm and is movable by the diaphragm relative to the other valve member against the said resilient bias.

9. An injector device as claimed in claim 1, in which the pressure-responsive member is operable to increase the area of the metering orifice in response to an increase in fuel pressure at the injector device inlet.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 2 695 518 Dated October 3 97 HAROLD ERNEST JACKSON .[nventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[30] Foreign Application Priority Data.

December 2, 1969 Great Britain 58789/69 Signed and sealed this 13th day of.Pebruary 1973.

(SEAL) EDWAR) IJ LIE'TCHERJR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM PO-I SO (10-69) Q USCOMM-DC 60376-P69 Q u.s GOVERNMENT PRINTING OFFICE: I969 o-ass-aaA 

1. A fuel injector device for a fuel injection system of an internal combustion engine, including a fuel inlet, a fuel outlet and a fuel flow path between the inlet and the outlet, first and second valve members which are movable relative to each other, the first valve member being a tubular element having, in the outer curved surface thereof, a fuel port which communicates with the bore of the tubular element and cooperates with the second valve member to define a fuel metering orifice in the said fuel flow path, the fuel port extending in the direction of the said relative movement and having a cross-sectional area which varies along the fuel port in that direction whereby the area of the metering orifice is adjustable by relative movement between the valve members, and a pressure-responsive member exposed to fuel pressure at the injector device inlet and coupled to at least one of the valve members to cause relative movement between the valve members and thereby adjust the area of the metering orifice in response to variations in that fuel pressure.
 2. An injector device as claimed in claim 1 in which the cross-sectional area of the fuel port varies through variations in two dimensions of the cross-sectional shape of the fuel port.
 3. An injector device as claimed in claim 2, in which the fuel port has a substantially triangular cross-section and the base and height of the triangle vary along the fuel port in the direction of the said relative movement.
 4. An injector device as claimed in claim 3, in which the base and height of the triangle both increase together along the fuel port in the direction of the said relative movement.
 5. An injector device as claimed in claim 1, in which the valve members are movable relative to each other in the direction of the longitudinal axis of the first valve member.
 6. An injector device as claimed in claim 1, in which the second valve member is a casing member within which the first valve member is located.
 7. An iNjector device as claimed in claim 1, in which the pressure-responsive member is a resilient diaphragm.
 8. An injector device as claimed in claim 7, in which one of the valve members is resiliently biased into engagement with the diaphragm and is movable by the diaphragm relative to the other valve member against the said resilient bias.
 9. An injector device as claimed in claim 1, in which the pressure-responsive member is operable to increase the area of the metering orifice in response to an increase in fuel pressure at the injector device inlet. 